<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="box">
    <div id="father">
      <div id="son"></div>
    </div>
  </div>

  <script>
    var son = document.querySelector('#son')
    var father = document.querySelector('#father')
    var box = document.querySelector('#box')

    console.log(son)

    console.log(father)
    console.log( son.parentElement )  // 父元素  
    console.log( son.parentNode.parentNode )  // 父节点

  </script>
</body>
</html>